ABSTRACT
Nowadays, face masks play an essential role in limiting coronavirus diffusion. However, their disposable nature represents a relevant environmental issue. In this work, we propose the utilization of two types of disposed (waste) face masks to prepare hard carbons (biochar) by pyrolytic conversion in mild conditions. Moreover, we evaluated the application of the produced hard carbons as anode materials in Na-ion batteries. Pristine face masks were firstly analyzed through infrared spectroscopy and thermogravimetric analysis. The pyrolysis of both mask types resulted in highly disordered carbons, as revealed by field-emission scanning electron microscopy and Raman spectroscopy, with a very low specific surface area. Anodes prepared with these carbons were tested in laboratory-scale Na-metal cells through electrochemical impedance spectroscopy, cyclic voltammetry and galvanostatic cycling, displaying an acceptable specific capacity along a wide range of current regimes, with a good coulombic efficiency (>98% over at least 750 cycles). As a proof of concept, the anodes were also used to assemble a Na-ion cell in combination with a Na3V2(PO4)2F3 (NVPF) cathode and tested towards galvanostatic cycling, with an initial capacity of almost 120 mAhg−1 (decreasing at about 47 mAhg−1 after 50 cycles). Even though further optimization is required for a real application, the achieved electrochemical performances represent a preliminary confirmation of the possibility of repurposing disposable face masks into higher-value materials for Na-ion batteries.
ABSTRACT
Sulfamethoxazole (SMX) is a frequently used antibiotic for the treatment of urinary tract, respiratory, and intestinal infections and as a supplement in livestock or fishery farming to boost production. The release of SMX into the environment can lead to the development of antibiotic resistance among the microbial community, which can lead to frequent clinical infections. SMX removal from water is usually done through advanced treatment processes, such as adsorption, photocatalytic oxidation, and biodegradation. Among them, the advanced oxidation process using TiO2 and its composites is being widely used. TiO2 is a widely used photocatalyst; however, it has certain limitations, such as low visible light response and quick recombination of e-/h+ pairs. Integrating the biochar with TiO2 nanoparticles can overcome such limitations. The biochar-supported TiO2 composites showed a significant increase in the photocatalytic activities in the UV-visible range, which resulted in a substantial increase in the degradation of SMX in water. The present review has critically reviewed the methods of biochar TiO2 composite synthesis, the effect of biochar integration with the TiO2 on its physicochemical properties, and the chemical pathways through which the biochar/TiO2 composite degrades the SMX in water or aqueous solution. The degradation of SMX using photocatalysis can be considered a useful model, and the research studies presented in this review will allow extending this area of research on other types of similar pharmaceuticals or pollutants in general in the future.
ABSTRACT
The global coronavirus disease 2019 (COVID-19) pandemic has rapidly increased the demand for facemasks as a measure to reduce the rapid spread of the pathogen. Throughout the pandemic, some countries such as Italy had a monthly demand of ca. 90 million facemasks. Domestic mask manufacturers are capable of manufacturing 8 million masks each week, although the demand was 40 million per week during March 2020. This dramatic increase has contributed to a spike in the generation of facemask waste. Facemasks are often manufactured with synthetic materials that are non-biodegradable, and their increased usage and improper disposal are raising environmental concerns. Consequently, there is a strong interest for developing biodegradable facemasks made with for example, renewable nanofibres. A range of natural polymer-based nanofibres has been studied for their potential to be used in air filter applications. This review article examines potential natural polymer-based nanofibres along with their filtration and antimicrobial capabilities for developing biodegradable facemask that will promote a cleaner production.